This invention relates generally to a double-hung window assembly having pivotal sashes and more particularly, to an improved sash constructed from extruded plastic framing members having novel latching means associated therewith at the corner box or butt joints of the sash.
Known double-hung window assemblies provide for inward tilting or pivoting of the two sashes by means of rotating members at the bottom ends of the sash balance mechanisms. Normal vertical reciprocal movement of the sashes is maintained by latch mechanisms disposed at the top margins of the sashes. The latch mechanisms usually include some manner of latch bolts that can slide along guide rails extending vertically of the master frame jambs. Releasing the latch mechanisms permits the sash to be pivoted inwardly for cleaning and/or servicing of the window glass pane.
Recently, such window assemblies and sashes have been formed of extruded synthetic plastic. In U.S. Pat. No. 4,144,674, extruded plastic members of one, uniform, cross-sectional configuration are fabricated to form the master frame while extruded plastic members of another, uniform cross-sectional configuration are fabricated to form the frame of each sash. Each sash has two latching mechanisms fastened onto the top surface of the header and two pivot pins fastened onto the top surface of the header and two pivot pins fastened onto the bottom surface of the base. The sash frames have miter-jointed corners. Hollow configurations of the sash framing members function to provide insulation against heat loss through the sash frame.
Fabrication of such a frame occurs by inserting the four frame members in a jig and clamping them together until adhesive applied to the miter-joints sets. This requires waiting time for setting of the adhesive and perfectly joined corners is a very difficult and often inconsistent achievement. Often, the extruded members are slightly warped or mitered imperfectly so that mating end edges that are intended to abut fail to do so. The result is non-mating miter joint and edges that are readily discernible because of the slivers of light that can pass through the joint in a direction normal to the plane of the sash. Such slivers of light leakage signal air and heat leakage rendering the particular sash undesirable for use in a home or office where heating costs are important.
The completion of such a sash requires the addition of the latch mechanisms and pivot pins. Previously, the latch mechanisms were applied external of the sash header with a suitable covering or guiding plate, or if internal, in a groove of the header, with a similar covering or guiding plate to close the groove. These covers and/or grooves add to the cost of the sash.
More recently, the sash frame members have been joined together by combination internal members of the miter joints. See U.S. patent application Ser. No. 602,382 filed Apr. 20, 1984, now U.S. Pat. No. 4,578,903. That application discloses combination support and connector members having a pair of leg segments perpendicular to one another. Each leg has a cross-sectional configuration complementary to that of the sash frame members to facilitate installation of the combination member legs in the mating miter ends of the frame parts. The combination members then are secured to the frame members by fasteners such as screws.
Newly developed sash frames have box or right angle butt joints instead of miter joint corners. The sash frame members have longitudinal hollows therein, and when joined in box or butt joints, the hollows are exposed. Thus, it would be useful to provide latch mechanisms including portions that further serve to join the frame members together while closing off the open ends of the frame members.